Electronic musical instruments with small tone generators adjacent key switches



Oct. 27, 1970 MAMORU KURIYAGAWA E 3,536,819

ELECTRONIC MUSICAL INSTRUMENTS WITH SMALL TONE GENERATORS ADJACENT KEY SWITCHES Filed June 21, 1968 4 Sheets-Sheet 1 G. I I 1284 I 12 lg 9%. 3; 9 4239 I 11; L 11 L H JL lTEJL L L. p N L g 54 K 556059 F|G 2 1 JW'\ 11 1 g M 432 fi ifik i 1 58 43 34 3 1 WWW W [W BY INVENTORS MAMORU KURIYAGAWA ETAI- 3,535,319

GENERATORS ADJACENT KEY SWITCHES 4 Sheets-Sheet 2 MA CWW INVENTORS 4 /LE t ('3 {I 119 44 w N: m

ELECTRONIC MUSICAL INSTRUMENTS WITH SMALL TONE Filed June 3 21, 1968 mO. mwzww 220 m Oct; 27, 1970 MAMORU KURIYAGAWA ETAL 3,536,819

ELECTRONIC MUSICAL INSTRUMENTS WITH SMALL TONE GENERATORS ADJACENT KEY SWITCHES 4 Sheets-Sheet 5 Filed June 21, 1968 M 0m v m m fi Z M Q l 8 x mm? WM Wm m mm, 8% m mm o, w 5 9 91 2 Q 8 K N2 wwwm Nw mm ,R on 6, 2: om w. 09 m9 m 0 n in mm 5 mm 0N R ow mm Q N? B 5 0m mm mm mw mm mm E 6 mm 80 :2 mm 3 w E 8 V 0-- w Ii? 1% H I :H \wufl ilu I 1 W1; 1 WPQPWPT- .WTIHETII 4 L Oct. 27,1970 MAMORU KURIYAGAWA ETAL 3,536,819

- ,ELECTRONIC MUSICAL INSTRUMENTS WITH SMALL TONE GENERATORS ADJACENT KEY SWITCHES Filed June 21, 1968 F G I 4 Sheets-Sheet A F G. W I

United States Patent US. Cl. 841.01 Claims ABSTRACT OF THE DISCLOSURE In an electronic musical instrument comprising a plurality of keys and a plurality of musical tone signal generators, each of musical tone signal generators is located close to an associated key in a space having a width smaller than that of the key right beneath or on the extension thereof.

This invention relates to improvements relating to electronic musical instrument including key board.

As is well known in the art the term electronic instruments are used to designate such musical instruments as organs, pianos and the like which operate to produce musical tones by electric circuits.

In conventional electronic instruments there are such disadvantages that the combined structure of key switches and musical tone signal generators is not only very com plicated but also induces noises. This is because that the conventional electronic musical instruments, for example, electronic organs, are constructed as follows: More particularly, while key switches are disposed closely adjacent white or black keys that comprise a key board, musical tone signal generators of musical intervals corresponding to respective keys are installed near the expression pedal at the lower portion of the instruments together with a source of electric supply. A plurality of, for example, four musical tone signal generators or generating circuits, with their intervals different from each other by one octave, are grouped in one group, and there are many such groups for each musical instrument. Output terminals of each musical tone signal generators are connected to a corresponding key switch through lead wires.

However, such method of wiring between the musical tone signal generating circuit and the associated key switch requires relatively long lead wires of more than one meter in the average, and the number of such connecting wires must be more than twice that of keys. As a result, wired lead wires become congested, which necessitates complicated wiring operations thus resulting in erroneous connections. Also these wiring operations require much time, thus reducing working efliciency and constituting a neck in the manufacturing of electronic organs. Even with correct wirings, as key boards or key switches are remotely located from their associated musical tone signal generating circuits, it is troublesome to inspect coincidence between a particular key and its corresponding musical tone signal generating circuit. Lead wires are connected to high impedance output terminals of the musical sound tone generating circuit of the order of more than several ten kiloohms to couple low level sound signals of less than few volts to the key switch but long wiring distance referred to above affects the signal-to-noise ratio. Also the distributed capacitance of lead wires themselves distorts the waveform of sound signals thus causing noises.

One approach to these problems is to dispose the musical sound signal generating circuits as close as possible to key boards thus reducing the length of lead wires as far as possible. Actually, however, such arrangement was not realized because of various problems involved. Thus, for example, wirings between key switches and musical sound tone signal generating circuits are again complicated thus requiring complex wiring steps. Furthermore construction of conventional key switches is not suitable and mere disposition of musical tone signal generating circuits near key boards causes mutual interference thus degrading the signal-to-noise ratio.

According to this invention electric musical instruments of simple construction without requiring long lead wires are provided by closely disposing respective musical tone signal generators adapted to generate sound signals of the musical intervals corresponding to respective keys in a space having a width smaller than that of the key right beneath or on the extension thereof.

Accordingly, one object of this invention is to provide electronic musical instruments of simple construction so that they can be produced in a mass production scale with simple manufacturing steps.

Another object of this invention is to provide electrical musical instruments having high signal-to-noise ratios.

This invention can be more fully understood from the following description taken in connection with the accompanying drawings, in which:

FIG. 1 shows a diagrammatic representation of a key board arrangement embodying this invention;

FIG. 2 is a circuit diagram of a musical tone signal generator employed in the arrangement shown in FIG. 1;

FIG. 3 shows a block diagram illustrating the relationship between a musical tone signal generator and a humanic generator;

FIG. 4 is an upper plan view of essential portions of one embodiment of this invention:

FIG. 5 is a side elevation of the arrangement shown in FIG. 4;

FIG. 6 is a perspective view of a supporting structure for short circuiting;

FIG. 7 is a partial view of contact wires and wire anchoring members;

FIG. 8 shows a side view of a modified arrangement embodying this invention;

FIG. 9 is a diagrammatic representation of the key board arrangement shown in FIG. 8;

FIG. 10 is a partial enlarged view of the arrangement shown in FIG. 8; and

FIG. 11 shows an electrical connecting of a musical tone signal generator.

In the accompanying drawings, like parts are designated by the same reference numerals. FIG. 1 shows diagrammatically essential parts of an electronic organ constructed according to the principle of this invention. As shown, a key board 10 comprises a plurality of black and/ or white keys 11 which are linearly arranged according to predetermined musical scales as is well known in the art. One of the features of this invention lies in disposing musical tone signal generators closely adjacent to key boards without utilizing lead wires. To this end each of musical tone signal generators 12 is disposed to oppose each one of these keys in a space within the narrow side width L at one end thereof. Each musical tone signal generator 12 is connected to an output signal conductor to supply its output sound signal thereto under control of an associated key switch 13. As will be described later, the key switch has a novel construction and is mounted on an arm 15 secured to one end of a key 11.

With reference now to the detail of musical tone signal generators 12, each one of them disposed at a position corresponding to respective one of the keys 11 is constructed to generate a tone signal of an oscillation frequency corresponding to the musical interval of the particular key 11. Thus, for example, a musical tone signal generator 12B disposed in a space within the end width L of a key 113 belonging to a tone type B; is constructed to generate a signal having a fundamental frequency of 1976 hertzs. Actually, musical tone signal generators 12 are comprised of flip-flop circuits printed on a common substrate, and these generators have the same construction except their trigger circuits. The flip-flop circuit comprising respective one of musical tone signal generators may be 'well known conventional circuit as shown in FIG. 2.

More particularly, collector load resistors 27 and 28 are connected between collector electrodes 23 and 24 of a pair of transistors and 21 and a terminal 25 of a DC source through a resistor 26. A condenser is connected between one terminal of resistor 26 and a grounded terminal 29 to constitute a decoupling circuit. Emitter electrodes 31 and 32 are also connected to the grounded terminal 29. A parallel circuit including a resistor 34 and a condenser 35 is connected between the base electrode 33 of transistor 21 and collector electrode 23 of transistor 20. Similar parallel circuit including a resistor 37 and a condenser 38 is connected between the base electrode 36 of transistor 20 and the collector electrode 24 of transistor 21. A trigger pulse input terminal 39 is connected to collector electrodes 23 and 24 of both transistors respectively through collector trigger condensers 40 and 41. An output terminal 42 is connected to the collector electrode 24 of transistor 21 to supply trigger pulses to the flip-flop circuit in the succeeding stage. Supply of the output tone signal from the flip-flop circuit 12 or the tone signal generator is controlled by a key switch 13 diagrammatically shown by a dotted line rectangle, the construction thereof being described later in detail.

To the collector electrode 24 of transistor 21 is connected an output terminal 46 via a resistor 45, which is electrically connected to an intermediate terminal 47, which in turn, is connected to one end of a flexible contact wire 48. The flexible contact wire 48 is constructed to engage either a grounded terminal 491 or a short circuiting terminal 50. Also another intermediate contact 51 is connected to one end of a contact wire 52 engageable with the short circuiting terminal 50. These contact wires 48 and 52 are constructed such that they simultaneously engage or disengage the short circuiting contact 50. The intermediate terminal 51 is connected to an output signal conductor 431 for the 8 foot rank scale (fundamental scale). The input terminal 39 is also connected to a signal output terminal 54 via a resistor 53, which is connected to an intermediate terminal 55 connected to one end of another contact wire 56. The contact wire 56 is constructed to contact either a grounded terminal 492 or a short circuiting terminal 58. Further a contact wire is connected to another intermdiate terminal 59 to engage a short circuiting contact 58. Again contact wires 56 and 60 are constructed such that they simultaneously engage or disengage short circuiting contact 58. Both ground terminals 491 and 492 are connected together.

The musical tone signal generator 12 operates as follows. The trigger input terminal 39 is connected to a reference signal oscillator or a flip-flop circuit in the preceding stage which generates tone signals of a frequency one octave higher to receive a trigger pulse signal. For the purpose of description, a case wherein a sound signal of the type of the tone B having a fundamental frequency of 1976 Hz. is generated will now be considered with reference to FIG. 3. A signal wave of the trigonometric function of 3951 Hz. is impressed upon the trigger input terminal 39 from a master generator 70. Then the signal is directly applied to the intermediate terminal 55 whereas a signal having a frequency of one half of 3951 Hz. is applied to the intermediate terminal 47. Thus the signal appearing at the intermediate terminal is the 8 foot (fundamental) tone signal while that appearing at the terminal 55 is a 4 foot (overtone) tone signal. Assuming now that a key 11B.; is depressed, contact wires 48 and 52 and contact wires 56 and 60 would engage contacts 50 and 58 respectively so that said 8 foot tone signal and 4 foot tone signal are supplied to output signal conductors 431 and 432, respectively. Signals on these conductors are supplied to a tone coloring circuit 71, amplifier and mixed by the operation of amplifiers 72 and 73, passed through a tone filter 74 and finally lead to a loudspeaker 75 through an amplifier 76 as a sound signal having a harmonic construction. The circuit arrangement of the harmonic construction shaper is not limited to that illustrated in the drawings. The musical tone signal generator 12 illustrated in the drawings utilizes a flip-flop circuit which generates a signal of rectangular Waveform having a repetition frequency equal to that of the desired musical interval. Only higher harmonics of the square wave signal of odd multiple orders of the repetition frequency are present. Thus, an equivalent organ tone is formed by mixing together the 8 foot tone signal and the 4 foot sound signal having square waveforms referred to above. With only an 8 foot tone signal, satisfactory organ tones can be produced. As a result, when the key 11B.; is depressed a sound of a musical interval of 1976 Hz. can be produced. Whereas when the key 1113.; is in its normal state, the key switch 13 assumes a position such that contact wires 48 and 56 engage grounded terminals 491 and 492 to ground said tone signal.

The trigger pulse output terminal 42 of the flip-flop circuit 12B.; is connected to the trigger pulse input terminal 39 of the flip-flop circuit 12B for generating a tone signal of 988 Hz. This is equivalent to using a signal generator of the flip-flop circuit 12B; of the preceding stage which is one octave higher as the signal generator of the flip-flop circuit 12B Likewise the trigger pulse output terminal 42 of this flip-flop circuit 12B;; is connected to the trigger pulse input terminal 39 of the flip-flop circuit 12B in the succeeding stage which generates a tone signal one octave lower. Lead wires of substantially the same length can be used to interconnect output terminal 42 and input terminal 39 because the distances between these terminals correspond to one octave of the musical interval and are equal for respective octaves, thus simplifying the wiring operation.

FIG. 1 shows the connection and arrangement of trigger terminals of flip-flop circuits 12R; and 12B for type B tone alone. As can be clearly noted from this figure, tone signals of the same tone name can be produced by successively dividing to /2 the output signal from the master generator 70 of a predetermined frequency by the action of the flip-flop circuit. As a consequence with the key board construction shown in FIG. 1 tones covering the entire tone range of the key board can be produced by providing a master oscillator having an oscillation frequency equal to the fundamental frequency of the maximum musical interval of respective tones of 12 types tnd by repeating frequency division to /2 by successively triggering with the respective output pulses from flip-flop circuits 12 of respective tone type series. As mentioned hereinbefore wirings to supply trigger signals can be readily made by utilizing lead wires (not shown) of the same length.

In order to have better understanding of this invention, the detailed construction of a musical instrument embodying this invention will now be described with reference to FIGS. 4 to 7. Essential portions of the instrument are mounted on a substrate 80 made of wood. A key 11 comprising one element of a key board 10 is secured to one end of a metallic arm 15 by means of screws. A rod shaped guide pin 81 is mounted on the bottom of a key 11. The guide pin 81 is arranged to be received in a groove 84 formed by a pair of spaced apart side members 82 and 83 secured to the substrate 80. A bridging member 85 having a perforation through which the guide pin 81 vertically extends is secured on the upper surfaces of side members 82 and 83. A felt cushion 86 is secured to the upper surface of the bridging member 85 to receive the bottom of the key 11 when it is depressed. A pedestal 87 is secured on the substrate 80 in order to support arm 15 substantially at its center. The pedestal 87 supports a letter L shaped supporting member 88 having a pointed top 89 engaging a groove provided at the middle of the bottom surface of the arm 15 whereby the arm can tilt about the pointed top 89. To assure positive engagement between arm 15 and the supporting member 88 the central portion of the arm 15 is normally biased downwardly by means of a bias spring 150 which is coiled about a bolt 90 and held by its head 91. Bolt 90 extends through a perforation through the arm 15 and its lower end is threaded into the pedestal 87. To permit turning of the bolt 90 for the purpose of adjusting thebiassing force of the spring 150 a hollow space 92 is provided beneath the bolt 90.

At the free end of the arm 15 is secured a supporting structure 96 by means of a screw which holds conductive short circuiting pins 50 and 58, the detail of the supporting structure being shown in FIG. 6 in an enlarged scale. A musical tone signal generator 12 is mounted on the extension of arm 15, said signal generator 12 having a Width smaller than the transverse width L of a key 11. The musical tone signal generator 12 is printed on a substrate 93 which is integrally mounted on the base 80. A supporting structure 94 is secured on the base 80 and a letter L shaped metallic mounting member 95 is secured to the inclined side surface of the supporting structure 94. The substrate 93 is secured to the lower side of the mounting member 95 by means of screws at an angle with respect to the surface of the base 80. FIGS. 4 and 5 show an actual construction of the flip-flop circuit which is formed on the substrate 93 and is diagrammatically shown in FIG. 2. Intermediate terminals 47, 51, 55 and 59 are arranged along a straight line on the lower side of the supporting structure 96. Contact wires 48, 52, 56 and 60 are electrically connected to these terminals 47, 51, 55 and 59 respectively by soldering. Lower ends of contact wires 48, 52, 56 and 60 are embedded and secured to the printed wired substrate 93. Of course contact wires 48 and 56 are connected to signal output terminals 46 and 54 via a conductive layer shown in FIG. 4 whereas contact wires 52 and 60 are connected to signal output circuits 431 and 432 through conductive layers as shown in the drawing. Other wiring patterns on the substrate 93 are formed by conductive layers as shown in the drawing. These contact wires 48, 52, 56 and 60 are equally spaced, and the length of wires 52 and 60 is slightly shorter than that of other two conductors 48 and 56. Wire guide grooves 98 and 99 separated by partition walls 97 are provided on the outer end of the insulating supporting member 96 at positions opposing said wires 48, 52, 56 and 60 respectively, said partition walls 97 being connected to the base wall of said wire guide grooves 98 and 99. The short circuiting contact 50 consisting of a pair of metal rods is inserted in the center of the wire guide groove 98 through partition wall 97. Likewise the short circuiting contact 58 is inserted in the center of the guide groove 99. The short circuiting member 50 is common to the wire guide groove 59 while another short circuiting member 58 insulated from the short circuiting member 50 is common to the wire guide groove 99. Contact wires 48 and 52 are received in the groove 98 while contact wires 56 and 60 in the groove 99. However, as these contact wires 48, 52, 56 and 60 are normally received at shallow depth so as not to contact with short circuiting contacts 50 and 58, free ends of these conta'ct wires are engaged with a wire engaging member 100. As stated hereinabove, the key switch 13 is comprised essentially of contact wires 48, 52, 56 and 60, short circuiting members 50 and 58, supporting member 96 and wire engaging member 100. As shown in FIG. 5, the wire engaging memher comprises a stepped insulator which is constructed such that its upper surface 101 engages with free ends of contact wires 52 and 60 while the intermediate surface 102 engages with the free ends of contact wires 48 and 56. The wire engaging member 100 constructed as above described is secured by screws to a letter L shaped supporting member 103 which is connected to the supporting member through a base plate 104 as shown in FIG. 5. The grounded conductor 49 is secured to the intermediate surface 102 of the wire engaging member at portions at which the surface engages the contact wires 48 and 56. The grounded conductor or terminal 49 is connected to a grounded line 29 through a conductor not shown. Supply conductor 25 is connected to a DC source and signal output conductors 431 and 432 are connected to amplifiers 72 and 73 respectively. These conductors include suitable connectors such as plugs and jacks leading to the source and amplifiers. Of course these conductors are comprised by printed conductive layers.

The novel musical instrument operates as follows. Normally a predetermined source voltage is supplied to the musical tone signal generators 12 from the source conductor 25 to operate them to generate signals. However contact wires 52 and 60 are engaging the upper surface 101 of the wire engaging member 100 so that they are spaced apart from the short circuiting contacts 50 and 58. On the other hand contact wires 48 and 56 are engaging the intermediate surface 102 of the Wire engaging member 100 so that they are in contact with the grounded conductor 49. Consequently, the tone signals generated are grounded and would not be sent out from the musical tone signal generators 12.

When the key 11 is depressed to tilt the arm 15 around the pointed edge of the support 88, the structure 96 mounted on the free end of the arm 15 will be pushed up. Concurrently therewith contact wires 48 and 52 are pushed up as indicated by an arrow A to engage the short circuiting member 50 while the contact wires 56 and 60 are caused to engage short circuiting member 58. At this time, contact wires 48 and 52 are short circuited by the short circuiting member 50 while contact wires 56 and 60 are short circuited by the short circuiting member 58. As can be noted from the connection diagram shown in FIG. 2, intermediate contacts 47 and 51 and intermediate contacts 55 and 59 are connected together, respectively. Then the musical tone signals will be supplied to signal output conductors 431 and 432. These 8 foot tone signal and 4 foot tone signal constitute the output from the musical tone signal generator 12 and the output is shaped into the harmonic construction of the organ system through the circuit as shown in FIG. 3 and is finally converted into a music by the loudspeaker 75 in a manner well known in the art. When the supporting member 96 for the short circuiting members is pushed up, contact wires 48, 52, 56 and 66 makes wiping contact against short circuiting members 50 and 58 so that contact surfaces thereof are always kept clean. This is necessary to ensure positive contact between contact wires and short circuiting members thus eliminating noise at the key switch 13.

As described hereinabove, in the novel musical instrument, since each musical tone signal generator 12 is disposed adjacent each key in a space bounded by the shorter side and extension of two longer sides of the key, the musical tone signal generator can be connected to the associated key without utilizing long lead wires. Thus, it is possible to obtain electronic musical instruments which have small size, simple construction, do not require any wiring step of lead wires, easy to manufacture, and suitable for mass production. In addition, erroneous wirings can be prevented. Further, the signal-to-noise ratio can be improved because there is no fear of introducing noise such as hum into lead wires and because mutual interference among respective musical tone signal generators can be avoided. Further, it is easy to adjust and inspect musical tone signal generators associated with respective keys.

Althoughthe musical tone signal generators 12 shown in FIGS. 4 and 5 are comprised by flip-flop circuits including transistors, resistors, condensers and the like elements printed on the substrate 93, it is to be understood that these circuits 12 can be fabricated as a micro-modules or integrated circuits/For example, when an integrated circuit is utilized, such a circuit occupies a volume of only one circuit element shown in FIG. 5 so that it can be readily disposed in a space smaller than the transverse width of a corresponding key.

Modified embodiment of a novel electronic organ will now be described with reference to FIGS. 8 to 11 which show only essential portions thereof. The basic construction of this modification is identical to that of the previous embodiment except that the size of the organ has been reduced and the construction has been simplified by arranging musical tone signal generators, key switches and the like components right beneath a key board. More particularly a key board 108 is mounted on a frame shaped base 110. A key 109 constituting one element of the key board 108 is pivotally connected to a rear frame 111 of the base 110. Thus, the rear end of the key 109 is notched to form a recess 112. A side member 113 is provided integral with the rear frame 111 to oppose the recess 112, said side member 113 being formed with a recess 114 so as to receive the lower side wall of the recess 112. A vertical stub shaft 115 is provided to extend through the recess 112 with its lower end journaled in a bearing opening in the frame 111. A cushion 116 of felt is applied on the upper surface of the frame 111. A blind hole 117 is drilled through the lower surface of the key 109 near the front end thereof. A vertical shaft 119 is secured to the front frame 118 to loosely fit in the blind hole 117. To normally push up the key 109 a biasing spring 120 is disposed around a bolt 121 provided at a suitable position. The bolt 121 is threaded through a plate 122 secured to the lower surface of the frame 111. By turning the bolt 121 the biasing force of the spring 120 against the key 109' can be adjusted. When the key 109 is depressed, it will be rotated around the bearing 123 until the bottom of the opening 117 comes to engage the top of the shaft 119. Upon removal of the depression force the key will be restored to the original position by the biasing spring 120.

A bent arm 124 is connected to the center of the lower surface of the key 109 by screws, and a support 125 of the short circuiting member is connected to the lower end of the arm 124. Each musical tone signal generator 126 is mounted beneath each key in a space smaller than the transverse width L of the key 109. FIG. 9 clearly shows relative arrangement of each key 109 and corresponding musical tone signal generator 126. The circuit arrangement of one music tone signal generator 126 is shown in FIG. 11 which is substantially the same as that shown in FIG. 2. In this embodiment, the signal output circuit is simplified such that the 4 foot tone signal and the 8 foot tone signal are mixed beforehand at the signal output terminal 127 which, in turn, is connected to an intermediate terminal 128 connected to a contact wire 129. The contact wire 129 is arranged to be engageable with a pin shaped short circuiting terminal 130. Also a contact wire 132 is connected to another intermediate terminal 131 which is connected to a signal output conductor 43, said contact wire 132 being arranged to be engageable with a short circuiting member 130. Thus, the construction of the key switch 133 is simpler than that of the previous embodiment. The music tone signal generator 126 is formed as a micro-module and all elements thereof are encapsulated in an insulating block of the dimensions 1 cm. x 4 cm. x 2 cm., which is mounted on a print wired substrate 134. The substrate 134 takes a form of an elongated rectangle with its one end secured to a support 135 depending from the rear frame 111. The fore end of the substrate 134 is supported by frames 136 through supports 137. (Only one of them is shown in FIG. 8). As shown in FIGS. 8 and 9 each music tone signal generator 126 is mounted on the substrate 134 immediately beneath an associated key.

FIG. 11 shows the connection diagram of one musical tone signal generator in the form of a micro-module. Grounded terminal 29, source voltage supply terminal 25, output terminal 127 for tone signals consisting of mixtures of 4 foot and 8 foot signals, intermediate terminals 128, 131 and trigger signal input and output terminals 29 and 42 shown in FIG. 11 have corresponding pin electrodes 135 projecting from the micro-module structure 126 as shown in FIG. 8. These pin electrodes 135 also serve as supporting legs for the micro-module structure 126. These pin electrodes are received in openings in the substrate 134 and soldered thereto. Although all requisite conductors are printed on the substrate 134, conductors associated with the tone signal output terminals and signal output path 43 alone are shown in FIG. 10. As shown in FIGS. 10 and 11, contact wires 129 and 132 are electrically connected to intermediate terminals 128 and 131 respectively by soldering, the lower ends of these contact wires being embedded in and secured to the substrate 134. Contact wires have resiliency and are normally standing upright. The short circuiting member 130 is disposed to oppose both contact wires 129 and 132. As shown in FIGS. 8 and 10 the short circuiting member 130 is supported by said supporting structure made of an insulator. As shown in FIG. 10, a pair of contact wires 129 and 132 are contained in respective wire guide grooves 139 and 140 partitioned by partition walls 138. The short circuiting member 130 extends across wire guide grooves 139 and 140 and is supported by partition walls 138. Contact wires 129 and 132 are partially embedded in grooves 139 and 140 respectively and their outer ends are arrested by a wire stop 141 so that they are normally maintained out of engagement with the short circuiting member 130. To position the wire stop 141 in the desired position it is formed as a L shaped member, and secured to pins 142 upstanding from the opposite ends of the substrate 134.

The modified embodiment shown in FIGS. 8 to 11 operates as follows: It is assumed that a requisite operating voltage is supplied to musical tone signal generators 126 through a source voltage supply conductor, not shown. Normally as keys 109 assume horizontal position with contact wires 129 and 130 engaged with wire stop 141, no tone signal is supplied to the amplifier system. When a key 109 is depressed, supporting member is also moved downwardly until finally contact wires 129 and 132 engage and wipe the short circuit member and flexed in the direction shown by arrow B in FIG. 8. Thus, contact wires 129 and 130 are interconnected by the short circuiting member 130 to apply tone signals to the amplifier system through the conductor 43 whereby musical tone signals having the desired harmonic construction are produced through a filter. In this manner, musical tone signals having a musical interval corresponding to the depressed key 109 are produced. As can be clearly noted from the foregoing description, according to this embodiment too, novel key switches are utilized and each musical tone signal generator is disposed in a space narrower than the transverse width of a corresponding key so that no lead wire connection is required. In addition to various advantages identical to those of the previous embodiment, there are such advantages that the construction of this embodiment is smaller and simplified. Although above illustrated embodiments relates to electronic organs it should be understood that this invention can also be applied to electronic pianos. In any case, this invention contributes to widespread use of electronic musical instruments with key boards.

It should be understood that foregoing embodiments are illustrated only for the purpose of description and that many changes and modifications may be made without departing from the scope of the invention as defined in the appended claims.

What is claimed is:

1. An electronic musical instrument comprising a key board including a plurality of keys which are arranged in parallel according to predetermined order to musical scales with their longer sides perpendicular to a straight line, each of said keys being rotatably supported at an intermediate point of its ends; a group of musical tone signal generators comprising by semiconductor elements and disposed on a substrate, each of said musical signal tone generators being disposed close to an associated key in a space having a width smaller than that of said key and connected to each of said keys to generate signals having a frequency corresponding to the musical interval of the associated key; harmonic construction shaping means arranged to receive output signals from said group of musical tone signal generators to shape them into a musical tone signal having a desired harmonic construction; output signal transmitting circuit to commonly transmit signals derived out from the signal output terminal of said musical tone signal generators to said harmonic construction shaping means; a plurality of resilient contact wires, the ends on one side of said contact wires 'being secured to said substrate while the other ends are free, said contact Wires being spaced apart, arranged in parallel and divided into two groups, each one of said groups including at lease one contact wire, the fixed ends of contact wires of one group being electrically connected to said signal output terminals and the fixed ends of contact wires of the other group being electrically connected to said signal transmitting circuit; and a group of short circuiting conductors contained in said respective spaces, secured to associated connecting arms interlocked with said respective keys, and adapted to resiliently engage both groups of contact wires to electrically interconnect free ends thereof when said respective keys are operated.

2. An electric musical instrument according to claim 1 wherein said output signal transmission circuit and electrical connecting circuits adapted to connect signal output terminals of respective musical tone signal generators, fixed ends of said contact wires and signal transmission circuit on said substrate are comprised of printed wires.

3. An electric musical instrument according to claim 1 wherein each of said short circuiting members comprises a wall structure including a plurality of partition walls to form a plurality of Wire guide grooves to contain free ends of said plurality of contact wires, said wall structure being contained in said space and mounted on a connecting arm interlocked with an associated key and conductive short circuiting elements supported by said partition walls to extend across said guide grooves, said short circuiting elements being operated to resiliently engage said groups of contact Wires to electrically interconnect free ends thereof when the associated key is operated, and there is provided a wire engaging member positioned at a position facing to free ends of said contact wires, said wire engaging member having a surface adapted to engage free ends of said contact wires so as to prevent them from engaging said short circuiting elements when the key is not operated.

4. An electronic musical instrument according to claim 3 wherein each of said group musical tone signal generators mounted on said substrate is disposed on the extensions of longer sides of an associated key.

5. An electric musical instrument according to claim 3 wherein each one of said group of musical tone signal generators mounted on said substrate is disposed right beneath an associated key.

6. An electrical musical instrument according to claim 3 wherein said wire engaging member includes a wire engaging surface provided with a grounded conductor at portions adapted to engage the free ends of contact Wires with their fixed ends electrically connected to signal output terminals of said musical tone signal generator.

7. An electric musical instrument according to claim 3 wherein two groups of said contact wires have different lengths, that is, a group of contact wires having their fixed ends electrically connected to signal output terminals of the musical signal tone generator has a shorter length than those of the other group, said wire engaging member being a stepped configuration to engage contact wires of different lengths by different surfaces and said grounded conductor being arranged in the surface that engages shorter contact wires.

8. An electronic musical instrument according to claim 1 wherein said musical tone signal generators are formed by printed wires.

9. An electronic musical instrument according to claim 1 wherein said musical tone signal generators are formed as micro-modules.

10. An electronic musical instrument according to claim 1 wherein said musical tone signal generators are constructed by integrated circuits.

References Cited UNITED STATES PATENTS 2,895,366 7/1959 Schneeberger et a1 841 3,068,334 12/1962 Gibbs et al. 200l66 3,095,465 6/1963 Holman 841.0l 3,251,923 5/1966 Lund 84--1.01 3,443,017 5/1969 Jones 841.0l

WARREN E. RAY, Primary Examiner 

